Q142920: How to Create Unique Values on SQL Server 6.x

Article: Q142920
Product(s): Microsoft FoxPro
Version(s): 3.00 3.00b
Operating System(s): 
Keyword(s): kbcode kbvfp300 kbvfp600
Last Modified: 20-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 6.0 
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SUMMARY
=======

SQL Server 6.0 has a new Identity property that can be used to create a unique
value for each row in a table. The identity property allows the user to specify
a seed value and an increment value. This article gives example code that shows
how to use the new Identity property.

MORE INFORMATION
================

The Identity property must be used with an integer datatype. (int, smallint, or
tinyint). Only one identity column is allowed per table. Identity columns cannot
be updated and won't accept NULL values.

Sample Code
-----------

This example creates an Invoice table that has a starting invoice number of 1000
and increments by 1 for each new invoice record inserted.

  * Establish connection to an existing datasource define to a SQL Server 6.0
  * database.

    xhandle = sqlconnect()
    IF xhandle > 0
      WAIT WINDOW "Successfull Connection. Handle = "+str(xhandle)
    ELSE
      WAIT WINDOW "Bad connection."
      =errhand()
      RETURN
    ENDIF

  * Create a table called Invoice and define the Identity property for the
  * Invoice_no column - assuming that a table called invoice does not already
  * exist.

    x = SQLExec(xhandle,"Create table invoice (invoice_no INT" + ;
       "identity(1000,1),customer varchar(25),;
       amount money, inv_date datetime)")

    IF x < 0
      =errhand()
      RETURN
    ELSE
      WAIT WINDOW "Table created successfully"
    ENDIF

  * Insert some new invoices.

    x = SQLExec(xhandle,"Insert invoice (customer,amount,inv_date)" + ;
     " Values('Brown &  Assoc.',$40000,'01/01/96' )")

    IF x < 0
      =errhand()
      RETURN
    ENDIF

    x = SQLExec(xhandle,"Insert invoice (customer,amount,inv_date)" + ;
     "Values('Jones Inc.',$90000,'01/01/96' ) ")

    IF x < 0
      =errhand()
      RETURN
    ENDIF

    x = SQLExec(xhandle,"Insert invoice (customer,amount,inv_date)" + ;
     "Values('Golden Hedge',$25000,'01/01/96' )")

    IF x < 0
      =errhand()
      RETURN
    ENDIF

    x = SQLExec(xhandle,"Insert invoice (customer,amount,inv_date)" + ;
     "Values('CPUs R Us',$50000,'01/01/96' )")

    IF x < 0
      =errhand()
      RETURN
    ENDIF

  * Check the values inserted.

    x = SQLExec(xhandle,"Select * from invoice","Invoice")

    IF x < 0
      =errhand()
      RETURN
    ENDIF

    SELECT Invoice
    GO TOP
    BROWSE

  * Disconnect.

    x = SQLDisconnect(xhandle)

    IF x < 0
      =errhand()
      RETURN
    ENDIF

  * Error Handling Procedure

    PROCEDURE errhand

      =AERROR(myerror)
      CLEAR
      ? 'An error has occurred.'
      FOR n = 1 TO 7
        ? myerror(n)
      ENDFOR
      =SQLDisconnect(xhandle)

    RETURN

Additional query words: VFoxWin

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Keywords          : kbcode kbvfp300 kbvfp600 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b kbVFP600
Version           : 3.00 3.00b

=============================================================================

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